The Australian Transport Safety Bureau (ATSB) is Australia's national transport safety investigator. The ATSB's function is to improve safety and public confidence in the aviation, marine and rail modes of transport. The ATSB is Australia's prime agency for the independent investigation of civil aviation, rail and maritime accidents, incidents and safety deficiencies.

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REPCON

Mode

Aviation

Reference No.

AR201600078

Date reported

16 August 2016

Concern title

The missed approach procedure at Bunbury Airport

Concern summary

The concern related to the track of the missed approach procedure for the RNAV-E approach at Bunbury Airport as this takes an aircraft over an unlit mast on a hill but there are no altitude requirements to ensure there is separation with the mast.

Industry / Operation affected

Aviation: General aviation

Concern subject type

Aviation: Airspace

Reporter's concern

The reporter expressed a safety concern related to the missed approach procedure for the RNAV-E approach at Bunbury Airport.

The reporter advised that there is an unlit mast on a bearing of 095 degrees at 12 nautical miles from Bunbury Airport. The mast is 492 ft AGL and 1737 ft AMSL.

The missed approach procedure takes an aircraft in close proximity to the mast in question but does not specify an altitude an aircraft must meet by a distance from the airport to ensure separation with the mast.

When the airport is situated on the coast, why does the missed approach direct an aircraft toward this unlit mast, without simple procedures to ensure separation? Why does the missed approach procedure make a turn towards terrain when the ocean is nearby and much safer to transit being literally above mean sea level. This is a very busy time in the cockpit and having an unlit mast marked on a chart, is easily overlooked.

Reporter comment: In terms of aviation systems safety management, the current procedure seems to have a number of latent failures that could easily lead to an active failure - accident scenario.

Operator's response (Operator 1)

On review of the approach, Airservices notes that the missed approach procedure provides more than the minimum required obstacle clearance required when an aircraft is overhead the mast. An aircraft would have sufficient clearance of approximately 760 feet when overhead the mast based on a 2.5% climb gradient from the BUNEH waypoint. Airservices notes that the missed approach design is influenced by the proximity of Busselton airport and the need to provide separation from a holding pattern associated with the Busselton RNAV-Z RWY 21 approach.

In response to the reporter's suggestion to direct aircraft above the ocean, Airservices notes that the protection area for the above mentioned holding pattern is wider towards the ocean.

As a result, aircraft would be required to maintain an altitude of 1,400 feet for a longer period.

In addition, a missed approach towards the ocean would take an aircraft overheard the Bunbury town with potential adverse noise consequences.

Regulator's response (Regulator 1)

CASA has reviewed the REPCON and believes that Airservices comments address the reporter’s concerns accurately. The missed approach procedure provides more than the minimum required obstacle clearance required when an aircraft is overhead the mast.

A straight missed approach would conflict to a greater extent with the Busselton RNAV-Z RWY21, the missed approach design is influenced by the proximity of Busselton airport and the need to provide separation from a holding pattern associated with the Busselton RNAV-Z RWY 21 approach.

Although the noise issues associated with a missed approach to the right are not procedure design matters per se, a missed approach towards the ocean would take an aircraft overheard the Bunbury town with potential adverse noise consequences. The publication process must consider environmental effects would result in a ‘fail’ for such a design.

I am advised that an option that might be explored is a missed approach with a left turn on to a track greater than 082°, in order to generate more lateral separation with the tower. It is suggested that the Airservices Procedure Design Section make contact with the reporter of the REPCON to explain the reasons for the designs of the YBUN and YBLN instrument flight procedures and the philosophies followed, and to advise the reporter that the existing design will safeguard a missed approach with more than the required minimum obstacle clearance.

Although Airservices has assessed the information in the report, there appear to be discrepancies in the information provided for the tower.

• The reporter notes that the tower is 1,737 ft AMSL, 492' AGL.

• The Perth VNC shows the tower as 1,737 ft AMSL, 607' AGL.

• The DAP plate shows a tower in the approximate location as 1,687 ft AMSL.

ATSB comment

The ATSB contacted Airservices Australia before the response was sent to the reporter to ensure they were aware of the comments made by CASA. They sent the following response:

This procedure is due for review in early 2017. We will consider the feedback in our revalidation and investigate the tower height discrepancies. In the interim, a NOTAM for Bunbury has been published to address the issue.

We are happy to liaise with the reporter to answer any questions they may have in regards to the procedure.

Reporter response

The reporter did not wish to be identified in this case but did ask that when the review occurs, consideration be given to directing the missed approach away from the unlit tower as there are much safer options available.